Vázquez-Ovando J A, Molina-Freaner F, Nuñez-Farfán J, Ovando-Medina I, Salvador-Figueroa M
Graduate Program in Biological Sciences, National Autonomous University of Mexico, Mexico City, Mexico.
Institute of Ecology, Ecology of Biodiversity Department, National Autonomous University of Mexico, Hermosillo, Sonora, Mexico.
Genet Mol Res. 2014 Dec 12;13(4):10404-14. doi: 10.4238/2014.December.12.2.
Criollo-type cacao trees are an important pool of genes with potential to be used in cacao breeding and selection programs. For that reason, we assessed the diversity and population structure of Criollo-type trees (108 cultivars with Criollo phenotypic characteristics and 10 Criollo references) using 12 simple sequence repeat (SSR) markers. Cultivars were selected from 7 demes in the Soconusco region of southern Mexico. SSRs amplified 74 alleles with an average of 3.6 alleles per population. The overall populations showed an average observed heterozygosity of 0.28, indicating heterozygote deficiency (average fixation index F = 0.50). However, moderate allelic diversity was found within populations (Shannon index for all populations I = 0.97). Bayesian method analysis determined 2 genetic clusters (K = 2) within individuals. In concordance, an assignment test grouped 37 multilocus genotypes (including 10 references) into a first cluster (Criollo), 54 into a second (presumably Amelonado), and 27 admixed individuals unassigned at the 90% threshold likely corresponding to the Trinitario genotype. This classification was supported by the principal coordinate analysis and analysis of molecular variance, which showed 12% of variation among populations (FST = 0.123, P < 0.0001). Sampled demes sites (1- 7) in the Soconusco region did not show any evidence of clustering by geographic location, and this was supported by the Mantel test (Rxy = 0.54, P = 0.120). Individuals with high Criollo lineage planted in Soconusco farms could be an important reservoir of genes for future breeding programs searching for fine, taste, flavor, and aroma cocoa.
克里奥洛型可可树是一个重要的基因库，具有用于可可育种和选择计划的潜力。因此，我们使用12个简单序列重复（SSR）标记评估了克里奥洛型树（108个具有克里奥洛表型特征的品种和10个克里奥洛参考品种）的多样性和群体结构。品种选自墨西哥南部索科努斯科地区的7个群落。SSR标记扩增出74个等位基因，每个群体平均有3.6个等位基因。总体群体的平均观察杂合度为0.28，表明杂合子不足（平均固定指数F = 0.50）。然而，在群体内部发现了中等程度的等位基因多样性（所有群体的香农指数I = 0.97）。贝叶斯方法分析确定个体内有2个遗传簇（K = 2）。与此一致的是，一项分配测试将37个多位点基因型（包括10个参考品种）归为第一个簇（克里奥洛），54个归为第二个簇（可能是阿梅洛纳多），27个混合个体在90%阈值下未被分配，可能对应于特立尼达基因型。这一分类得到了主坐标分析和分子方差分析的支持，这两种分析表明群体间变异为12%（FST = 0.123，P < 0.0001）。索科努斯科地区采样的群落地点（1 - 7）没有显示出按地理位置聚类的任何证据，这得到了曼特尔检验的支持（Rxy = 0.54，P = 0.120）。种植在索科努斯科农场的具有高克里奥洛谱系的个体可能是未来寻找优质、口感、风味和香气可可育种计划的重要基因库。
